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diff --git a/doc/man/sat.1 b/doc/man/sat.1 new file mode 100644 index 0000000..635b518 --- /dev/null +++ b/doc/man/sat.1 @@ -0,0 +1,217 @@ +.TH SAT 1 SAT +.SH NAME +sat \- Queue a job for later execution. +.SH SYNOPSIS +.B sat +.I TIME +.IR COMMAND ... +.SH DESCRIPTION +.BR sat (1) +is a simple implementation of +.BR at (1). +But is not compatible with +.BR at (1). +It is used to queue jobs to be executed later, outside +the current controlling terminal. +.PP +.BR sat (1) +shall launch +.BR satd (1), +unless it is already running, and queue a specified +.I COMMAND +to be executed at a selected +.IR TIME . +The job shall be executed with the same environment +variables as +.BR sat (1) +had when the job was queued. +.PP +The +.I TIME +argument must be specified in one of four formats: +.TP +.IB HH : MM +The job shall be executed the next time the clock is +.IR HH : MM :00. +.I HH +may by any positive value. The time is specified in UTC. +.TP +.IB HH : MM : SS +The job shall be executed the next time the clock is +.IR HH : MM : SS . +.I HH +and +.I SS +may by any positive values. The time is specified in UTC. +.TP +.I S +The job shall be executed the next time the POSIX time +clock shows +.IR S . +That is, +.I S +seconds passed Epoch (1970-01-01 00:00:00 UTC), ignoring +leap seconds (hence "the next time".) +.TP +.BI + S +The job shall be executed in +.I S +seconds. +.PP +Nanosecond resultion in +.I TIME +is supported. +.B Z +or +.B UTC +can be added at the end if +.IB HH : MM +or +.IB HH : MM : SS +is used. This suppresses a warning telling you that the +time was interpreted as UTC. It is not possible to select +any other timezone, not even the local timezone. If the +specified time is in the passed, but not more than 24 +hours ago, 24 hours will be added to it, and a warning +is printed. This is so that you can use an external time +string parser without having to worry about its behaviour +too much. +.PP +If the +.BI + S +format is used, +.B sat +will use the +.B CLOCK_BOOTTIME +clock, for the other formats +.B CLOCK_REALTIME +is used. Note that this is +.B CLOCK_BOOTTIME +and +.BR CLOCK_REALTIME , +not +.B CLOCK_BOOTTIME_ALARM +and +.BR CLOCK_REALTIME_ALARM . +If you want to the the latter clocks, you may want to +look in the direction of +.BR sleep-until (1). +.PP +The +.B sat +utilities can also print and edit the list of queued jobs. +.PP +If you are using +.BR autohaltd (8), +you should set up hooks for +.BR at (1) +that pauses +.BR autohaltd (8) +using +.B SIGSTOP +(and resume with +.BR SIGCONT ) +when there are queued jobs. This would prevent +.BR autohaltd (8) +from shuting down the machine while there are queued jobs but +no logins. +.B sat +cannot stop +.BR autohaltd (8) +by adding login entries, because +.BR autohaltd (8) +will only recognise them if they are in fact true logins. +.SH OPTIONS +None. +.SH RATIONALE +.BR at (1) +is far too complex. +.PP +.B sat +does not do natural language time parsing, it is far too complex, +and locale dependent, for all programs to implement and should be +done in a separate program. Not even GNU +.BR date (1) +gets this right. +.B sat +does however do some trivial parsing. +.PP +.B sat +does not sanitise the environment. You have +.BR env (1) +for that. Relaying on +.B sat +to sanitise the environment appropriately could prove to be a +misfortune. +.PP +.B sat +does not do mailing because that is very restrictive, hooks are +used instead. +.PP +.B sat +does not do system load analysis, this should be done in a +separate program. +.PP +.B sat +only has one queue, queue can easily be emulated using dummy +commands, for example instead of \(aqmy command\(aq, you can +run \(aqsh -c ": QUEUE-a ; my command"\(aq. +.PP +.BR at (1) +should not be merged into +.BR cron (8). +.BR cron (8) +does recurring scheduled jobs, +.BR at (1) +does one-time unscheduled jobs. +.BR atq (1) +does not translate to +.BR cron (8). +.SH ENVIRONMENT +.TP +.B XDG_RUNTIME_DIR +This environment variable names the directory in which +interprocess communication related files are stored. If +unset or empty, /run is used. +.TP +.B SAT_HOOK_PATH +The pathname of the hook script to use. Does not have to +already exist. If not defined, $XDG_CONFIG_HOME/sat/hook +(if XDG_CONFIG_HOME is defined), $HOME/.config/sat/hook +(if HOME is defined), ~/.config/sat/hook (if the user has +a home and is not root), or /etc/sat/hook (otherwise) is +used. +.SH "FUTURE DIRECTIONS" +.B sat-atcompat +will be written to bring compatibility with old school +.BR at (1). +.SH NOTES +.BR nohup (1) +combined with +.BR sh (1) +and, +.BR sleep (1) +or +.BR sleep-until (1) +should be sufficient for most users. +.PP +.B sat +stores the job queue in a file. However, this file does not persist +between reboot. +.SH "SEE ALSO" +.BR at (1), +.BR cron (1), +.BR sleep-until (1), +.BR date (1), +.BR satq (1), +.BR satrm (1), +.BR satr (1), +.BR satd (1) +.SH AUTHORS +Principal author, Mattias Andrée. See the COPYING file for the full +list of authors. +.SH LICENSE +MIT/Expat License. +.SH BUGS +Please report bugs to https://github.com/maandree/sat/issues or to +maandree@member.fsf.org |